Kudos to Jim Van Nuland for giving us the heads-up on the subtle
illumination in Ptolemaeus. Here's another heads-up...
A few days ago I mentioned a sighting of my own favorite moon feature, Mare
Orientale. I've been fooling around with Virtual Moon Atlas lately, because
it's cloudy here in the Midwest, too. (I'm visiting my folks for the
holidays.)
It looks like we'll get another good Orientale libration during the next
lunation. Looks like January 7th through 13 will be fairly good, with the
10th probably being the most favorable libration. As the days go on, the
illumination of the Orientale area will get a little less 'overhead' and we
may see some shadows develop. I'm going to be using the Rukl map of that
part of the libration zone to see how many features I can identify.
I don't know if anyone's planning on going to Hogue on Friday the 9th,
given how full the moon will be, but Orientale might make a fun target once
the moon gets up.
If you haven't seen it, it's worth looking at the famous Lunar Orbiter 4
image of this area. One look and you can see why it's the youngest,
freshest, and most spectacular multi-ring impact basin:
http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/lo4_m187.html
Now, here's a possible project for the imagers... I think this would be
really cool...
Back in the pre-Apollo days, not long before the above image was taken by
Lunar Orbiter 4, the planetary scientists Gerard Kuiper and William
Hartmann hit upon a clever idea. They realized that if they took good
photos of the moon from the earth (e.g. from Lick) and projected them onto
big white globes, they could "rectify" the images of the limb areas. Upon
doing so, they found to their surprise that areas like Orientale were
enormous bulls-eyes, defined by huge circular mountain ranges. Thus the
idea of multi-ring impact basins was born.
In fact, Hartmann's recent "Travler's Guide to Mars" tells this story as
part of an aside on lunar geology, and shows the original "globe" image
compared to the Orbiter 4 image. (This book is worth its weight in gold, by
the way... it's awesome...) Hartmann has a page about it here:
http://www.psi.edu/hartmann/science.html
Anyway, I always thought it would be fun to see how good of a "globe" shot
could be obtained by an amateur imager. Maybe there's even a way to do the
"projection onto a globe" transformation digitally. I'm not an imager, so I
thought I'd throw this out there as an idea.
I'll be back in the Bay Area on the 29th. I have my fingers crossed for
clear skies. Happy Holidays!
Marek Cichanski